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The black liquor is a byproduct of the kraft pulping process that contains more than half of the exergy content in the total woody biomass fed to the digester, representing a key supply of renewable energy to the pulping process. In this work, the conventional scenario of the black liquor use (i.e., concentration and combustion) is compared with the black liquor upgrading (via) gasification process for ammonia production in terms of economics, exergy efficiency and environmental impact. The combined energy integration and exergy analysis is used to identify the potential improvements that may remain hidden to the energy analysis alone, namely, the determination and mitigation of the process irreversibility. As a result, the exergy efficiencies of the conventional and the integrated cases average 40% and 42%, respectively, whereas the overall emission balance varies from 1.97 to −0.69 tCO2/tPulp, respectively. The negative CO2 emissions indicate the environmental benefits of the proposed integrated process compared to the conventional kraft pulp mill.

A reverse osmosis system driven by photovoltaic energy is an eco-friendly and sustainable way to produce freshwater in rural areas without connection to a power grid and with available brackish water sources. This paper describes a project where a photovoltaic-driven low-pressure reverse osmosis system (LPRO-PV) was designed, tested under laboratory conditions, and installed in Samalayuca, Chihuahua, Mexico, to evaluate the technical feasibility and social impact of this technology. The LPRO-PV system was tested with synthetic water with a salinity of 2921 ± 62.3 mg/L; the maximum freshwater volume produced was 1.8 ± 0.06 m3/day with a salinity value of 91 ± 1.9 mg/L. The LPRO-PV system satisfied the basic freshwater requirements for a local family of three members for one year, including the mobility-restriction period due to the COVID-19 pandemic. The social evaluation analysis reflects the importance of considering the technical aspects derived from the experimental tests, as well as the users’ perception of the performance and operation of the system. As a result of the implementation of this technology and the benefits described by the users, they committed to the maintenance activities required for the LPRO-PV system’s operation. This technology has great potential to produce fresh water in arid and isolated regions with high-salinity groundwater sources, thus fulfilling the human right to safe and clean drinking water.

This article reports a model regarding the structural equations of the impact of the planning phase and the benefits acquired in the implementation of the kanban system. It begins with a literature review of the activities of the planning phase, based on which a questionnaire was developed and applied in manufacturing companies in the state of Baja California, in the municipalities of Ensenada, Tijuana, Tecate, and Mexicali. The responses were obtained from 118 questionnaires and were validated by the Cronbach’s alpha index for internal validity and the R-squared index for predictive validity. A model of the structural equations of the planning phase was developed and validated through three latent variables, namely, human resources, preliminary analysis, and kanban integration, which correspond to 22 activities and one variable that integrate 11 operational benefits. The model shows six hypotheses to verify the causal relationships between these variables. Partial least-squares algorithms are used to validate the hypothesis, and the results indicate that the preliminary analysis is the basis for the success of the implementation of the kanban in the planning stage, through the application of activities, such as 5’s, value stream mapping (VSM), material handling, flow diagram, and visual aids with a sustainable approach, according to the efficient flow of materials and minimum downtime.

Spain has been pinpointed as one of the European countries at major risk of extreme urban events. Thus, Spanish cities pursue new urban plans to increase their resilience. In this scenario, experiences in the implementation of Sustainable Urban Drainage Systems (SUDS) have increased substantially. Nevertheless, few cities have developed a global urban strategy for SUDS, lacking, in many cases, a method to identify strategic areas to maximize their synergetic benefits. Furthermore, there is still a need for a holistic Multicriteria Decision Analysis (MCDA) framework that considers the four pillars of SUDS design. The city of Gijón, NW Spain, has been selected as a case study due to its environmental and climatic stresses. This research presents the methodology developed for this city, which aims to analyze the need for SUDS implementation throughout the identification of strategic areas. With this aim, a combination of Geographic Information System (GIS) software and the MCDA Analytical Hierarchical Process (AHP) were proposed. The results show the potential for SUDS’ implementation, according to nine criteria related to the SUDS’ design pillars. We found that the areas where the implementation of SUDS would bring the greatest functional, environmental and social benefits are mainly located in consolidated urban areas.

This paper proposes the computation and assessment of optimal tilt and azimuth angles for a receiving surface, using a mathematical model developed at the University of Tomsk, Russia. The model was validated and analyzed for the Nuevo León State, Northeast Mexico, utilizing a set of metrics, comparing against satellite data from NASA. A point of interest in the city of Monterrey was analyzed to identify orientation patterns throughout the year for an optimal solar energy gathering. The aim is providing the best orientation tilt angles for photovoltaic or solar thermal panels without tracking systems. In addition, this analysis is proposed as a tool to achieve optimal performance in sustainable urban development in the region. Based on the findings, a set of optimal tilt and azimuth surface angles are proposed for the analyzed coordinates. The aim is to identify the optimal performance to obtain the maximum solar irradiation possible over the year for solar projects in the region. The results show that the model can be used as a tool to accelerate decision making in the design of solar harvesting surfaces and allows the design of discrete tracking systems with an increase in solar energy harvesting above 5% annually.

Abstract Decision-making for sustainable design requires the evaluation of different options considering all sustainability dimensions simultaneously: economic, environmental and social. Each dimension has a specific relative importance, which depends on the process that is being assessed. The determination of the relative importance is not a simple task, principally, during early design stages when detailed information about the process is scarce, and when core decisions affecting the entire design are made. An example of this kind of decisions during early design stages is the selection of the chemical process route, which, once defined, provides the guidelines for the process design. The present study proposes a multi-criteria analysis based methodology to evaluate different chemical process route options under sustainability criteria and to guide the selection among them. The methodology uses normalized indicators to assess each sustainability dimension, and a multi-criteria analysis method (MCDA) to calculate the weights and influences between dimensions. Indicators, dimension weights and influences are integrated into the Sustainable Cumulative Index ( SCI ) that can be used to compare chemical process route options in sustainability terms and to support their selection. The proposed methodology is illustrated through the assessment and selection of a chemical process route to produce ethyl acetate.

Landfills are one of the most common ways to dispose the solid urban waste in many countries due to their relatively simple technical requirements, operational costs and low investment. Moreover, biogas produced in landfills can be used as a renewable energy source for power generation. The Valencian Region is one of the largest solid urban waste producers in Spain, and therefore, it has an unexplored potential of landfill biogas production. This paper aims to estimate the potential of biogas landfill production for power generation in the Valencian Region. Statistical data from solid urban waste in landfills in the provinces of Alicante, Castellón, and Valencia was gathered. Then the potential of landfill biogas production was estimated by means of waste classification for each province. To provide information related to the use of landfill gas as an alternative source of energy, results presented in this work show that the Valencian Region has an important potential to use landfill biogas from solid urban waste as a renewable source for power generation, and also provide information to the regional government, academic researches, policy makers and investors.